1. Field of Invention
This invention relates generally to visual displays and to gyricon or twisting-element displays.
2. Description of Related Art
Gyricon, or twisting, particles, such as balls and cylinders, are used to make gyricon displays. A gyricon display is also referred to as electric paper. A gyricon display comprises twisting particles that individually rotate to display a desired surface or a desired aspect of transparency of the particles to an observer.
Twisting particles can be, for example, a ball having two distinct hemispheres with both an optical anisotropy and an electrical anisotropy due to each hemisphere surface having a different color and electrical charge. The twisting particles are generally embedded in a fluid-filled cavity of a substrate. The substrate is then generally bonded between glass or plastic sheets to create a gyricon display. When an electric field is presented over the display, the twisting particles within the substrate rotate in reaction to the electric field by rotating in the fluid. U.S. Pat. Nos. 4,126,854 to Sheridon and 4,143,103 to Sheridon each incorporated herein by reference in its entirety, describe conventional twisting ball displays each.
Gyricon displays ideally have characteristics and qualities of conventional paper, such as flexibility. However, conventional gyricon displays are not paper-like because they are generally too rigid. A further discussion of the disadvantages of conventional gyricon displays is found in U.S. Pat. No. 5,064,027 to Sheridon, which is incorporated herein by reference in its entirety.
In an effort to make the gyricon displays more paper-like, attempts have been made to individually encapsulate the twisting particles. This is called microencapsulation. Microencapsulated twisting particles are then incorporated into a flexible substrate without needing a protective sheet of glass or plastic.
A conventional approach to microencapsulating a twisting particle centers on a chemical process where the twisting particles are first produced using conventional methods and then are subsequently immersed and treated in chemical solutions, resulting in a capsule, as disclosed in the ""027 patent.
Chemical methods of microencapsulating gyricon beads require numerous additional steps in making a display and thus add substantially to the cost of making the display. Further, there is a limited yield in the chemical methods and errors occur that are difficult to eliminate. Among the errors it is found that some microcapsules do not contain balls and others contain two or more balls. Capsules that do not contain balls subtract from the contrast of the display and capsules that contain two or more balls do not exhibit good ball rotation because of interference between the balls, again causing a loss in contrast. Still further, the chemical processes used in producing the microencapsulation of the balls have been found to be incompatible with the chemistry of the balls, on occasion, limiting the types of balls that can be microencapsulated.
This invention provides methods of both fabricating gyricon beads and in the same instant process, microencapsulating each said ball singly in a liquid-filled capusle.
This invention separately provides methods of microencapsulating a twisting particle. This invention separately provides methods for microencapsulating a twisting particle, that do not use chemical processes.
This invention separately provides methods for making a micro-capsule containing a bichromal bead and a liquid that engulfs the bichromal bead.
This invention separately provides a method for making a microencapsulated gyricon bead based on the differences of the surface tensions of the respective materials that form various layers and/or portions of the microencapsulated gyricon bead.
These and other features and advantages of this invention are described in, or are apparent from, the following detailed description of various exemplary embodiments of the systems and methods according to this invention.